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2011 NIAID Year In Review

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Antibodies Identified After 2009 H1N1 Infection Neutralize Multiple Flu Virus Strains

NIAID-supported investigators have shown that infection with the 2009 H1N1 influenza (flu) virus triggers the production of antibodies that can neutralize multiple flu strains, known as broadly neutralizing antibodies. These results suggest that it may be possible to develop a universal human influenza vaccine that could protect against both seasonal strains of the virus and newly emergent strains.

Investigators analyzed blood plasmablasts, antibody-producing cells that appear shortly after infection, taken from nine people approximately 10 days after infection with 2009 H1N1. These cells produced antibodies that could neutralize many different strains of influenza virus, including seasonal H1N1 viruses and the 1918 H1N1 pandemic virus, which killed millions of people. Further study showed that these antibodies bound to specific sites on the hemagglutinin molecule, a protein attached to the surface of the influenza virus via a stem-like region. Most of these antibodies bound to the stem-like region, which is known to vary little from strain to strain.

illustration of an influenza virus particle

Influenza (flu) virus particle (cross section). The pink spikes represent hemagglutinin molecules attached to the surface of the virus.
Credit: NIAID

In laboratory experiments, the antibodies protected human cells from becoming infected with several different flu viruses, and at least two of the antibodies protected mice from potentially lethal doses of the 2009 H1N1 flu virus. Such broadly neutralizing antibodies to flu virus have rarely been seen in people after infection or vaccination.

The researchers speculate that multiple exposures to seasonal flu viruses and vaccines over the years have given rise to immune cells known as memory cells that recognize parts of the virus that vary little between strains. Targeting the conserved region of the hemagglutinin may lead to the development of a universal flu vaccine.

Reference: Wrammert J, Koutsonanos D, Li GM, Edupuganti S, Sui J, Morrissey M, McCausland M, Skountzou I, Hornig M, Lipkin WI, Mehta A, Razavi B, Del Rio C, Zheng NY, Lee JH, Huang M, Ali Z, Kaur K, Andrews S, Amara RR, Wang Y, Das SR, O'Donnell CD, Yewdell JW, Subbarao K, Marasco WA, Mulligan MJ, Compans R, Ahmed R, Wilson PC. Broadly cross-reactive antibodies dominate the human B cell response against 2009 pandemic H1N1 influenza virus infection. J Exp Med. 2011 Jan 17;208(1):181-93.

Last Updated January 08, 2013

Last Reviewed January 08, 2013